In geothermal operations, hot water or steam is flowed from a subterranean location and its energy converted to useful form such as power for electric generators, etc.
A problem associated with geothermal wells is their tendency to scale up in the flash zone. Release of pressure reduces the solubility equilibrium of salts (e.g. CaCO.sub.3) in the water as the water converts to steam. This results in scale deposition at or near the flash zone. If not inhibited the deposits will reduce the flow area and plug the well pipe used to conduct the geothermal fluid to the surface.
Conventional scale inhibitors such as phosphonates and polyacrylates are not thermally stable at high temperatures and for that reason are not effective in the treatment of high temperature (above 400.degree. F.) geothermal wells.